SALENID^. 35 



the small number of primary coronal plates, the strueture of the radioles 

 and secondary spines, arc Cidaridean features of considerable importance, 

 yet the structure of the plates of the buccal membrane, the gill slits of the 

 actinal interambulacral plates, the presence o£ ophicephaloiis pedicellaria;, 

 the disconnected ambulacral auricles, their low, wide, interainbulacral ridgr-s, 

 the presence of a deep foramen in the pyramid of the jaws, which are not 

 almost solid, as in the Cidaridae, are all features of the Echinidie far out- 

 weighing the Cidaridean characters which had originally led me to consider 

 them as more closely allied to the Cidarida3. In addition, the existence of 

 demiplates in the actinal region of the ambulacra and the slight crowding 

 of the actinal ambulacral plates are important features allying them to the 

 Echinidae. To group together the Salenidae and the Aspidodiadematidae 

 as Diadematoida, as is suggested by M. de Meijere, can only bring endless 

 confusion. 



It has become evident from the abundant material of Salenise col- 

 lected since the first recent species was described,^ that the typical Salenia 

 varispina was only a very young specimen from which but few of the 

 characters of the modern SaleniaB could be ascertained. As Solenia varispina 

 was not as fully figured as other species, I have added for the sake of com- 

 parison not only additional figures oi S. varispina (PI. 21), but also a few figures 

 of S. Pattersoni (PL 20, figs. 5-7) and of S. hastigera (PI. 20, fig. 8) to assist 

 the identification of these species. 



The original S. varispina measured only 1.9 mm. in diameter. The 

 abactinal system covered nearly the whole of the upper part of the test 

 (PI. 21, fig. i?), and was much larger in proportion than in a small S. miliaris 

 of 5 mm. in diameter, in which the coronal plates formed a wide zone round it. 



The genital and ocular plates are striated diagonally (PI. 21, fig. 8), 

 and a few sessile verrucas edge these plates, with one or two near the 

 edge of the anal system. Those of the madreporic genital are seen more 

 magnified (PI. 21, fig. 7) from the exterior, and the same plate is seen from 

 the interior (PI. 21, fig. 8) to show the accumulation of limestone cells form- 

 ing the madreporic body. Both figures show the character of the striation 

 of the apical plates ; it does not pass from one plate to the adjoining one, 

 the striae butt against the sutures. This diagonal striation, towards the acti- 

 nal suture in the younger coronal plates and towards the abactinal suture 

 in older plates, seems to give us the explanation of the movement of the 



1 Salenocidaris varispina A. Ag., 1869, Bull. M. C. Z. p. 254. Revision of the Echini, p. 261. 



